As the price of energy sources has increased due to exhaustion of fossil fuel and concern about environmental pollution has been amplified, the demand for environmentally friendly alternative energy sources has increased as an essential factor for future life. In particular, a recent trend for multiple functions, high performance, and miniaturization of mobile devices has increased the demand for a secondary battery having high capacity while having a small size.
In terms of the shape of batteries, the demand for prismatic secondary batteries or pouch-shaped secondary batteries, which are thin enough to be applied to products, such as mobile phones, is very high. In terms of the material for batteries, the demand for lithium secondary batteries, such as lithium ion batteries and lithium ion polymer batteries, having high energy density, discharge voltage, and output stability, is very high.